1. Field of the Invention
The present invention is related to a cooing fan without returning flow and particularly to a cooling fan, with which airflow at the outlet can be increased largely without producing a stagnation zone for expanding cooling area and attenuating noise.
2. Brief Description of the Related Art
Due to electronic components being developed rapidly to increase their running speeds, much more heat is generated from the electronic components too. Thus, how to dissipate heat properly for the electronic components being capable of running smoothly is an important subject that has to be faced by designers of the electric components.
Referring to FIGS. 1 to 4, the conventional cooling fan 1 includes a motor stator 11 and a motor rotor 12. The stator 11 has a bearing sleeve 111 and the bearing sleeve 111 is surrounded with a coil 112. The hub 121 of the rotor 12 is attached with a fan blade set 122. The hub 121, which has a shaft 121a and a magnet 123, is placed inside the hub 121. After the rotor 12 is mounted to the stator 11, the motor 12 can rotate by way of the coil 112 and the magnet 123 acting with each other. Referring to FIG. 5, when the cooling fan runs, the airflow generated from the fan blade set 122 can form an airflow stagnation zone behind the hub 121 and it results in the airflow being unable to move smoothly. Thus, the overall effect of heat dissipation of the cooling fan is influenced significantly.